LAS VEGAS — Robert Guerrero has a lot to anticipate in his near future, some scary and some exciting.

The former two-time titleholder will hear next week whether his wife Casey’s bone marrow transplant was effective. Casey has been battling leukemia and doing well lately. If the news is good, he could be looking at another shot at a major title.

Guerrero returned from an eight-month layoff, spent by his wife’s side, to knock out journeyman Robert Arrieta of Argentina at 29 seconds of the eighth round of a scheduled 10-round lightweight bout Friday night at the Tropicana Hotel.

He has an eye on the winner of the Juan Manuel Marquez-Juan Diaz rematch on July 31 in Las Vegas, a realistic possibility because all three fighters are with Golden Boy Promotions.

Marquez holds two 135-pound titles.

“I still have a lot on my mind,” said Guerrero, who had to cancel a title defense in March because of his wife’s illness and subsequently gave up his belt. “This week my wife got a bone-marrow biopsy. I’m itching to find out about that. That’s going to tell us whether a bone-marrow transplant worked or not. That’s in the back of my mind.

“ÔǪ It’s a tough juggling act. When you’re a professional athlete, though, sometimes you have to block it out and take care of business.”

Guerrero (26-1-1, 18 knockouts) took care of business against Arrieta (35-16-4, 17 KOs) on Friday, although it tested his patience.

The former featherweight and junior lightweight titleholder, fighting at 135 for only the second time, controlled the fight from the beginning but had difficulty taking out his reluctant opponent.

Guerrero put Arrieta down in both the second and third rounds with straight lefts and a knockout seemed inevitable. After that, though, it seemed Arrieta didn’t want any part of his superior opponent.

“The tough part about it ÔǪ as soon as I hit him, he went into survival mode,” he said. “When they do that, they’re the hardest guys to get to. ÔǪ I just tried to be patient and let it work.”

It worked in the eighth round. Guerrero landed a huge left that put Arrieta down and hurt him. The Argentine was able to get up but, under a barrage of punches, couldn’t defend himself well enough to go on and the fight was stopped.

Guerrero gave his performance a “C,” saying he has a lot of work to do, but he said the only thing that felt unfamiliar after his eight-month hiatus was the cheering of the crowd.

“I’m not used to it,” he said. “I’m used to being home with my wife taking care of business. It was exciting. It gets you going. A few times I got anxious to take him out but you gotta be cautious.”

Now Guerrero is eager to take the next step, the Marquez-Diaz winner being his prime target. He said he doesn’t care who wins. The Gilroy, Calif., resident, bubbling with enthusiasm after his KO Friday, just wants another big fight.

“I know God is great and will give us great news next week,” he said. “Then I’ll go full force and be ready to anything.”

On the undercard, former amateur standout Frankie Gomez (2-0, 2 KOs) stopped Ricardo Malfavon (0-2) at 1:06 of the second round of a scheduled four-round welterweight bout.

The East Los Angeles prospect landed a monster right that sent journeyman Malfavon spinning to the canvas. The Santa Ana, Calif., fighter was able to stagger to his feet but couldn’t continue.